Safaei Mohsen, Meneghini R Michael, Anton Steven R
Department of Mechanical Engineering, Tennessee Technological University, Cookeville, TN 38505 USA.
Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN 46202 USA, and also with Indiana University Health Physicians Orthopedics and Sports Medicine, IU Health Saxony Hospital, Fishers, IN 46037 USA.
IEEE ASME Trans Mechatron. 2018 Apr;23(2):864-874. doi: 10.1109/TMECH.2018.2794182. Epub 2018 Jan 15.
The knee replacement is one of the most common orthopedic surgical interventions in the United States; however, recent studies have shown up to 20% of patients are dissatisfied with the outcome. One of the key issues to improving these operations is a better understanding of the ligamentous balance during and after surgery. The goal of this work is to investigate the feasibility of embedding piezoelectric transducers in the polyethylene bearing of a total knee replacement to act as self-powered sensors to aid in the alignment and balance of the knee replacement by providing intra- and postoperative feedback to the surgeon. A model consisting of a polyethylene disc with a single embedded piezoelectric ceramic transducer is investigated as a basis for future work. A modeling framework is developed including a biomechanical model of the knee joint, a finite element model of the knee bearing with encapsulated transducer, and an electromechanical model of the piezoelectric transducer. Model predictions show that a peak voltage of 2.3 V with a load resistance of 1.01 Ω can be obtained from a single embedded piezoelectric stack, and an average power of 12 can be obtained from a knee bearing with four embedded piezoelectric transducers. Uniaxial compression testing is also performed on a fabricated sample for model validation. The results found in this work show promising potential of embedded piezoelectric transducers to be utilized for autonomous, self-powered in vivo knee implant force sensors.
膝关节置换术是美国最常见的骨科手术干预措施之一；然而，最近的研究表明，高达20%的患者对手术结果不满意。改善这些手术的关键问题之一是更好地理解手术期间和术后的韧带平衡。这项工作的目标是研究将压电换能器嵌入全膝关节置换术的聚乙烯轴承中的可行性，使其作为自供电传感器，通过向外科医生提供术中和术后反馈来辅助膝关节置换术的对齐和平衡。研究了一个由带有单个嵌入式压电陶瓷换能器的聚乙烯盘组成的模型，作为未来工作的基础。开发了一个建模框架，包括膝关节的生物力学模型、带有封装换能器的膝关节轴承的有限元模型以及压电换能器的机电模型。模型预测表明，单个嵌入式压电堆栈在负载电阻为1.01Ω时可获得2.3V的峰值电压，带有四个嵌入式压电换能器的膝关节轴承可获得12的平均功率。还对制造的样品进行了单轴压缩测试以验证模型。这项工作中发现的结果表明，嵌入式压电换能器有潜力用于自主、自供电的体内膝关节植入力传感器。
